1 ½ tsp. aluminium-free baking powder
1 tsp. baking soda
1 ½ tsp salt
227g unsalted butter, cut into ½-inch cubes (I used Tillamook)
3/4 cup lightly packed dark brown sugar
3/4 cup sugar
3 eggs
1 tsp. vanilla extract
227g/8 oz. bittersweet chocolate, roughly chopped into ¼- and ½-inch pieces (I used Lindt 70%)
2) Put the butter and sugars in the bowl and whisk with hand-held whisk or stand-mixer until the butter and sugars are blended, about 2 minutes. Scrape down the sides of the bowl with a spatula.
3) Add the eggs one at a time, beating well after each addition.
4) Beat in the vanilla. Add the flour mixture to the bowl, and blend on low speed until the flour is just incorporated. Scrape down the sides and bottom of the bowl.
5) Add the chocolate, and mix until evenly combined. Scrape down the sides and bottom of the bowl, and then use your hands to turn and gently massage the dough, making sure all the flour is absorbed.
6) Chill dough in fridge for one day before baking.
7) Next day, preheat oven to 180degreesC. Position racks in upper and lower third of oven. Use an ice-cream scoop to scoop each cookie, leaving about 3 inches between each cookie. If you, like me, don't have an ice-cream scoop, just roll similar-sized balls of dough in your hands instead. But you have to act fast because the dough goes runny easily.
8) Bake the cookies for 15 to 20 minutes, rotating the sheets halfway through, until the cookies are evenly browned. Transfer the cookies, still on parchment, to a rack to cool. Store in airtight container for up to a week (if they even last that long). After the first day, just slightly warm them up in a toaster oven before eating, to make them extra moreish.